In general, vacuum or reduced pressures preserve food from chemical oxidation, decomposition or decay resulting from the propagation of bacteria, and thus vacuum storage has been widely applied to food or perishables. For example, application of vacuum storage can be found in canned food, retorted food and the like. However, a canning or retorting device is too large to preserve a small amount of food, thus making it difficult to store food for a family with a light appetite. In addition, the smaller the amount of food to be treated, the lower is the operation efficiency of the canning device.
For these reasons, there has been developed a device for bagging food. In this device, the food to be stored is put into a flexible bag such as a polyethylene bag, and the bag is deaerated and then hermetically sealed. Such a device makes it possible to produce bagged food with ease, but it is difficult to store food for a long period of time as a large amount of air remains in the bag. In addition, it is difficult with such a device to store liquid food.
To solve such problems, a vacuum storage system has been proposed in Japanese patent application serial No. 63-47654 (corresponding to U.S. Pat. application Ser. No. 287121), that comprises a base plate with a bellows pump, a cover member hermetically and removably mounted on a body to form a pressure reducing chamber, and a closable vessel adapted to be housed in the chamber and used for storing food. In this system, food to be stored is firstly put into the closable vessel, and the vessel is closed with a lid member having a port with a check valve. The closed vessel is then placed in the chamber formed between the base plate and cover member mounted thereon, and the air in the closed vessel is drawn out by the bellows pump.
However, such a vacuum storage device has various disadvantages awaiting a solution. For example, the air in the closed vessel is drawn out by the pressure difference between the closed vessel and the chamber. Thus, it is required to draw out a large amount of air contained in the chamber having a considerably large volume as compared with that of the closed vessel, resulting in a decrease in the pressure reduction efficiency and considerable increase in the time required for the pressure in the closed vessel to be reduced to the desired value. In addition, the vacuum storage system can be operated on the table, but it occupies a relatively large part of the surface area of the table.